1. Field of the Invention
The present invention relates to an image scanning device that is configured to scan an image from a manuscript.
2. Background Information
Some image forming devices (e.g., photocopier) and image scanning devices (e.g., scanner) are provided with a function of automatically detecting the manuscript size and automatically selecting the size of the image data to be outputted and the transfer medium (e.g., paper) so that the image data and the transfer media are fitted to the detected manuscript size.
A technology for detecting a manuscript on a glass platen by way of a light sensor has been known as an example of detection technology for the manuscript size. In addition, a technology for detecting the manuscript size by the combination of the output signals of a light sensor when a platen cover is opened and closed has been proposed.
As an example of the above described technology, Japanese Examined Patent Publication No. H07-3554 discloses a photocopier that includes a manuscript size detector, a platen glass, a platen cover that is openably/closeably disposed to cover the platen glass, an optical system for scanning a manuscript on the platen glass, and four manuscript size detectors. Each of the manuscript size detectors is made up of a light-emitting element for irradiating light to the platen glass from the bottom of the platen glass, a lens for forming an image on the upper surface of the platen glass with the light irradiated by the light-emitting element, a light-receiving element for detecting light reflected by the manuscript on the platen glass, and a lens for forming an image on the light-receiving surface of the light-receiving element with the reflected light. The manuscript size detectors are disposed so that their focal positions on the platen glass are different from each other. In the photocopier, the manuscript size is distinguished by the combination of output signals produced by the manuscript size detectors.
In the photocopier, the light irradiated by the light-emitting element is reflected by the manuscript in the area on the platen glass where the manuscript exists. Therefore, light enters the light-receiving element regardless whether the platen cover is opened or closed, and accordingly the signal output from the manuscript size detector will be in an on state. Also, as to a black part on the manuscript, the amount of reflected light is small regardless of whether the platen cover is opened or closed. Therefore, the signal output will be in an off state. On the other hand, while the platen cover is opened, the light irradiated by the light-emitting element is neither reflected by the manuscript nor the platen cover in the area on the platen glass where the manuscript does not exist. Therefore, the amount of light received by the light-receiving element is small, and accordingly the signal output from the manuscript size detector will be in the off state. However, light is reflected by the platen cover while the platen cover is closed. Therefore, the amount of light received by the light-receiving element is increased, and accordingly the signal output of the manuscript size detector will be in the on state.
As described above, according to the photocopier described in the above patent reference, it has been determined that a manuscript does not exist in a position where the signal output is switched between an on state and an off state by opening and closing the platen cover, and it also has been determined that a manuscript exists in a position where the signal output is not changed by opening and closing the platen cover. Based on the judgments, the manuscript size will be determined.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved image scanning device. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.